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Comp Biochem Physiol C Toxicol Pharmacol. 2018 Sep;211:7-14. doi: 10.1016/j.cbpc.2018.05.003. Epub 2018 May 21.

Does size matter? Venom proteomic and functional comparison between night adder species (Viperidae: Causus) with short and long venom glands.

Author information

1
Venom Evolution Lab, School of Biological Sciences, University of Queensland, St Lucia, QLD 4072, Australia.
2
Centre for Advanced Imaging & Centre for Microscopy and Microanalysis, University of Queensland, St Lucia, QLD 4072, Australia.
3
Princess Alexandra Hospital, Translational Research Institute, University of Queensland, St Lucia, QLD 4072, Australia.
4
Mtoxins, 1111 Washington Ave, Oshkosh, WI 54901, USA.
5
Faculty of Health Sciences, University of Macau, Avenida da Universidade, Taipa, Macau, China; Jiangsu Key Laboratory for Functional Substance of Chinese Medicine, School of Pharmacy, Nanjing University of Chinese Medicine, 138 Xianlin Avenue, Qixia District, Nanjing 215400, China.
6
Faculty of Health Sciences, University of Macau, Avenida da Universidade, Taipa, Macau, China.
7
Venom Evolution Lab, School of Biological Sciences, University of Queensland, St Lucia, QLD 4072, Australia. Electronic address: bgfry@uq.edu.au.

Abstract

Night adders (Causus species within the Viperidae family) are amphibian specialists and a common source of snakebite in Africa. Some species are unique in that they have the longest venom glands of any viper, extending approximately 10% of the body length. Despite their potential medical importance and evolutionary novelty, their venom has received almost no research attention. In this study, venoms from a short-glanded species (C. lichtensteinii) and from a long-glanded species (C. rhombeatus) were compared using a series of proteomic and bioactivity testing techniques to investigate and compare the toxin composition and functioning of the venoms of these two species. Both C. rhombeatus and C. lichtensteinii were similar in overall venom composition and inhibition of blood coagulation through non-clotting proteolytic cleavage of fibrinogen. While the 1D gel profiles were very similar to each other in the toxin types present, 2D gel analyses revealed isoformic differences within each toxin classes. This variation was congruent with differential efficacy of South African Institute for Medical Research snake polyvalent antivenom, with C. lichtensteinii unaffected at the dose tested while C. rhombeatus was moderately but significantly neutralized. Despite the variation within toxin classes, the similarity in overall venom biochemistry suggests that the selection pressure for the evolution of long glands served to increase venom yield in order to subjugate proportionally large anurans as a unique form of niche partitioning, and is not linked to significant changes in venom function. These results not only contribute to the body of venom evolution knowledge but also highlight the limited clinical management outcomes for Causus envenomations.

PMID:
29758383
DOI:
10.1016/j.cbpc.2018.05.003
[Indexed for MEDLINE]

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